#include<stdio.h>
double result_real, result_imag;

void complex_prod( double x1, double y1, double x2, double y2 )
{
    result_real = (x1*x2 - y1*y2);
    result_imag = (x1*y2 + x2*y1);
}


int main(void) { 
    double imag1, imag2, real1, real2;    

    scanf("%lf %lf", &real1, &imag1);             
    scanf("%lf %lf", &real2, &imag2);             
    complex_prod(real1, imag1, real2, imag2);     
    printf("product of complex is (%f)+(%f)i\n", result_real, result_imag);    return 0;
}